Laser-induced ionisation spectroscopy, particularly for coal

ABSTRACT

An apparatus for analyzing material, such as coal, comprises subjecting the coal ( 14 ) to laser light. The laser light is used to vaporize and ionize a small amount of the coal to produce spectral emissions. A plurality of detection, ( 26, 30, 34 ) each of which detect a part of the spectrum emissions, collect spectral information and pass it to data collection means ( 38, 40, 42 ). The data is then analyzed to determine the presence and/or amount of one or more elements or species in the coal. In a preferred embodiment, the apparatus has a plurality of data collection means ( 26, 30, 34 ), with each of the plurality of detection means being associated with a respective data collection means ( 38, 40, 42 ). The apparatus provides rapid and accurate analysis of the coal. The apparatus may be used to analyze coal on conveyor belt or coal in a seam in the ground.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method for analysing amaterial. The present invention is particularly suitable for analysingcoal and for convenience the invention will hereinafter be describedwith reference to its application in analysing coal. However, it will beappreciated that the invention should not be considered to be restrictedto the analysis of coal.

Coal is a fossil fuel source that has carbon and hydrocarbons as itsmain constituents. In addition, coal also contains lesser, althoughstill significant, amounts of silicon, aluminium; iron, calcium, sodium,potassium and other elements. These species generally report to the ashafter the coal has been combusted. Some coals, such as Victorian browncoals, also contain appreciable quantities of water.

It would be desirable to be able to analyse coal in two situations. Thefirst of these involves analysis of the coal in-situ in the coal seam toassist in~ short term mine planning and to also be able to provide amore accurate estimate of the value of coal in the seam. The secondapplication involves analysis of the coal shortly before or duringcombustion. This could assist in predicting the likelihood of foulingand slagging in a coal-fired boiler or combustor, thereby enablingpreventative action to be taken. Fouling and slagging deposits are amajor difficulty in the power generation industry and the severity ofthese deposits depends upon the inorganic constituents in the coal.

A number of techniques have been described that provide for coalanalysis. Known analytical techniques for determining the composition ofcoal in a coal seam typically require the extraction of a sample ornumber of samples from the seam and returning the samples to alaboratory for conventional coal analysis of coal as described on page9.4 of Perry et. al., “Chemical Engineer's Handbook”, 5th Edition,McGraw Hill International Book Company, 1974.

U.S. Pat. No. 4,562,044, in the name of Bohl (assigned to The Babcockand Wilcox Company) describes a method and apparatus for the on-lineanalysis of a coal sample. The apparatus includes four radial arms eachcarrying a sample cup. An indexing motor indexes each sample cup along acircular path past a filling station where the cup is filled withpulverised coal. The cup then passes to an analysing station wherevarious chemical analyses are performed. The cup then moves to a dumpingstation and a cleaning station, following which the cup is again readyfor filling with pulverised coal.

U.S. Pat. No. 4,841,153 in the name of Wormald (assigned to CogentLimited) relates to an analysis system and method for analysing coal inwhich the coal is bombarded by neutrons to generate gamma rays. Thegamma rays are detected and the composition of the coal determinedtherefrom.

Other detectors bombard the coal with gamma rays or x-rays. Such systemsrequire stringent safety precautions to be taken to avoid thepossibility of exposing operating staff to x-rays or gamma rays.

Another technique that has been reported as being used on a laboratoryscale for coal analysis is. laser-induced breakdown spectroscopy (LIBS)or laser spark emission spectroscopy. In this technique, a high energylaser (normally pulsed) is used to vaporise and ionise a small amount ofmaterial for analysis. The vaporised material or laser-induced breakdownplasma produces strong optical emission. Spectroscopic analysis of theoptical emission gives information about the properties of the materialbeing analysed. A discussion of one technique using LIBS is given in apaper by Ottesen et. al. entitled “Laser Spark Emission Spectroscopy forIn-Situ, Real Time Monitoring of Pulverised Coal Particle Composition”,published by Sandia National Laboratories (No. SAND 90-8586), on behalfof the Department of Energy, printed August 1990.

Although LIBS techniques have shown promise as being suitable for coalanalysis, the present inventors are not aware of the technique beingapplicable beyond the laboratory scale, due to difficulties whichinclude spectral line interference, slow sampling and response times,and calibration uncertainty.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improvedapparatus and method for the analysis of material.

In a first aspect, the present invention provides an apparatus foranalysing a material comprising a laser for impinging laser light ontothe material to vaporise and ionise at least part of the material and tocause spectral emissions therefrom, a plurality of detection means fordetecting spectral emissions from the material, each of said pluralityof detection means detecting a part of the spectrum of the spectralemissions, a plurality of data collection means to collect data fromsaid plurality of detection means on said spectral emissions wherebyeach of the plurality of detection means is associated with a respectivedata collection means, and determining means to determine the presenceand/or amount of one or more elements or species in the material.

Each of the plurality of detection means may comprise a spectrometeradjusted to a part of the spectral region. Each of the spectrometers mayhave a CCD detector associated with the spectrometer. The CCD detectormay pass information on the spectral region to a data acquisition cardor a data file in a computer or memory space. This data may then beanalysed to determine the presence of one or more elements or species inthe material and preferably to determine the amount or concentration ofthe element or species in the material.

Spectrometer types suitable for use in the present invention includegrating and prism spectrographs; interferometers, such as etalon andscanning interferometer types; and filters, including coloured glass orinterference filter types which allow transmission or reflection of aportion of the spectrum.

Detectors other than CCD's (charged-coupled detectors) may also be used.Other detectors that may be used in the present invention includephotodiode arrays, vidicons, photomultiplier tubes and photodiodes. Theperson skilled in the art would readily appreciate which detector(s)should be used.

Preferably the apparatus further comprises control means for controllingfiring of the laser and for controlling and synchronising operation ofthe plurality of detection means. The control means may include a timingcircuit to fire the laser at specified times and to operate thedetection means at other specified times. It is especially preferredthat the control means also synchronises operation of each of theplurality of detection means such that the plurality of detection meanssimultaneously detect spectral emissions from the material.

In place of the timing circuit, the control means may comprise controlsoftware to control operation of the laser and the detection means.

The apparatus will also include one or more optical systems to focus thelaser light on the material and to focus the spectral emissions on theplurality of detection means. The one or more optical systems mayinclude one or more lenses, optical fibre, prisms, beam splitters orother optical components. Although suitable optical systems arerequired, it will be understood that the design of the optical systemdoes not form part of the invention concept of the present invention andthe person skilled in the art will be able to design a large number ofsuitable optical systems without requiring inventive ingenuity.Accordingly, the optical system(s) need not be discussed further.

The laser may be any laser capable of causing vaporisation andionisation of a part of the material. Suitable lasers include solidstate lasers such as the 1064 nm Nd:YAG laser, harmonic wavelengths ofthe Nd:YAG laser, i.e. 532 nm, 355 nm and 266 nm; gas lasers such asexcimer lasers, e.g. 308 nm XeCl, or 248 nm KrF excimer lasers; carbondioxide lasers; liquid lasers such as dye lasers; or anywavelength/frequency shifting, harmonic generation or mixing of theabove. Lasers other than those specifically mentioned may also be used.The person of skill in the art will readily be able to select anappropriate laser.

The apparatus of the present invention may be suitable for analysingmaterial in a laboratory, on a conveyor or in the ground.

The apparatus of the present invention enables high resolution ofelemental fluorescence to be obtained and largely avoids or minimisesspectral interferences common in known LIBS analysers. The presentinvention also enables detection of a large spectral range in a singlelaser pulse thereby greatly decreasing time for analysis. This reducedtime for analysis allows the apparatus to be used as a real-timeanalytical tool. It also minimises sampling errors. In this regard, theapparatus can obtain an analysis of a number of elements in that portionof the material vaporised in each laser pulse. In contrast, known LIBSapparatus required sequential analysis of the material which meant thata number of laser pulses were required. Each laser pulse would vaporisea different part of the material which could lead to errors,particularly if the material being analysed has pronouncedheterogeneity.

The present invention also relates to a method for analysing a material.

In a second aspect, the present invention provides a method foranalysing a material comprising subjecting said material to laser lightto at least partly vaporise and ionise said material to thereby causespectral emissions, detecting said spectral emission with a plurality ofdetection means, each of said plurality of detection means detecting apart of the spectrum of the spectral emission, collecting data from aplurality of detection means and analysing said data to determine thepresence and/or amount of one or more elements or species in thematerial wherein the step of collecting data from the plurality ofdetection means comprises passing spectral information from theplurality of detection means to data acquisition cards associated witheach of the plurality of detection means.

The method may further comprise controlling operation of the laser andthe plurality of detection means.

DESCRIPTION OF THE DRAWINGS

The apparatus and method of the present invention will now be furtherdescribed with reference to a preferred embodiment of the presentinvention. In the accompanying drawings:

FIG. 1 is a schematic drawing of an apparatus in accordance with anembodiment of the present invention;

FIG. 2 shows an analysis of coal obtained using the apparatus inaccordance with the present invention;

FIG. 3 shows an arrangement incorporating the present invention forin-situ analysis of coal;

FIG. 4 shows an alternative arrangement for analysing coal in a coalseam;

FIG. 5 shows an embodiment of the present invention being used foron-conveyor analysis; and

FIG. 6 shows an alternative arrangement of the present invention foron-conveyors analysis of coal.

DETAILED DESCRIPTION OF THE INVENTION:

In the following description of a preferred embodiment of the presentinvention, the method and apparatus of the invention was used to analysecoal. However, it will be appreciated that the method and apparatus ofthe present invention may be used to analyse a wide range of materials.The materials that may be analysed by the method of the invention may besolid, liquid or even gaseous. In the apparatus shown in FIG. 1, a laser10, which may be a 1064 nmNd:YAG laser, emits pulses of laser light thatare focused by an optical system 12 onto a material to be analysed 14.In the small region of the laser spot focused on the material 14, thelaser power density produces rapid heating and ionisation of a smallsample of the material. Light is emitted from the vaporised and ionisedmaterial containing spectral information on the material involved. Thelight emitted from the vaporised and ionised material is schematicallyrepresented at 16 and this emitted light 16 is passed through objectivelens 18 and then is detected by a plurality of detection means 20, 22,24. The apparatus shown in FIG. 1 has three detection means but it willbe appreciated that a lesser or greater number of detection means may beutilised. It is envisaged that a greater number of detection means maybe utilised if especially high resolution is required. Detection means20 comprises a spectrometer 26 that is adjusted to a part of thespectrum of the spectral emissions emanating from material 14. Detectionmeans 20 also includes a CCD detector 28 which suitably comprises areadily available commercial CCD detector. The CCD detector 28 maycomprise a 12-16-bit detector.

Similarly, detection means 22 comprises a spectrometer 30 and a CCDdetector 32. Detection means 24 also comprises a spectrometer 34 and CCDdetector 36.

The CCD detectors 28, 32, 36 detect information from the specificspectral region provided by their associated spectrometers. The CCDdetectors then pass the detected information to respective dedicateddata acquisition cards 38, 40, 42 which are associated with a centralcomputer 44. The data acquisition cards may include analog-to-digitalconversion boards/circuitry. The computer 44 also includes control means46 to control the operation of the laser 10 and the plurality of thedetection means 20, 22, 24.

In use of the apparatus shown in FIG. 1, the control means 46 sends acontrol signal to laser 10 which causes the laser to emit a pulse oflaser light. The pulse of laser light 10 is focused onto the surface ofmaterial 14 which causes vaporisation and ionisation of a small part ofthe material 14.

Shortly after the control signal causes a pulse of laser light 10 to beemitted by the laser, the control means 46 sends control signals to thedetection means 20, 22, 24 which turns on those detection means. It ispreferred that there is a slight delay between firing of the laser andinitialisation of operation of the spectrometers in order to ensure thatthe CCD detectors do not detect the pulse of laser light and only detectthe emitted spectra. This control signal causes the spectrometers 26,30, 34 to collect light from the relevant spectral region for apredetermined period of time and to enable the CCD detectors 28, 32, 36to detect that light. Each of spectrometers 26, 30, 34 collect lightfrom particular regions of the emission spectrum. The particular regionsmay be discrete, separate regions of the spectrum, or there may be someoverlap between the spectral region collected by one of thespectrometers and the spectral region collected by another of thespectrometers. Whilst the detection means 20, 22, 24 are collecting anddetecting the light from the emitted spectral region from the sample 14,the CCD detectors are also forwarding information to the respective dataacquisition cards 38, 40, 42. The CCD detectors are formed fromindividual areas of light sensitive material (usually silicon) known aspixels. Each pixel converts the light intensity to an electric change orcurrent which is then digitised by the data acquisition cards. The useof separate data acquisition cards for each detection means enablesrapid collection of large amounts of data and this in turn allows therapid analysis of the material to take place at high spectralresolution.

The data collected by the data acquisition cards 38, 40, 42 is thenanalysed by the computer to determine the elements or species present inthe material and also to determine the relative amounts of each of thoseelements or species. The amount of each element or species in thematerial may be determined by integrating the area under the spectralline at a wavelength that is characteristic of the spectral emission ofa given element or species and comparing that area with the area underthe same spectral line obtained from a material having a known contentof that particular element or species.

Print outs of the spectral emission data collected from an apparatus inaccordance with the present invention is shown in FIG. 2. FIG. 2 hasbeen marked to show the spectral lines for ion, calcium, sodium,hydrogen, carbon, magnesium, silicon, and aluminium.

Since the apparatus allows the measurement of coal components includingcarbon (C), hydrogen (H) and oxygen (O)—as well as ash formingcomponents,—it also allows determination of fuel properties relevant toutilisation of the coal, in particular the coal heating (calorific)value and water content.

The apparatus and method of the present invention preferably detectsspectral emissions from the material being analysed in the visible lightrange. However, the apparatus may also detect long wavelength infraredand short wavelength ultra violet radiation.

The apparatus of the present invention provides an apparatus thatenables high resolution determination of a range of materials. Detectionof a large spectral range in a single laser pulse is possible, whichgreatly reduces the time taken for analysis. This in turn leads to areduction in sampling errors because all of the elements being analysedare present in that portion of the sample vaporised in each laser pulse,compared to the laser vaporising different pieces of sample whenelements are analysed sequentially. Although a single pulse of laser issufficient to enable analysis of a wide range of elements in thematerial, sound sampling techniques will utilise information collectedand analysed from a plurality of laser pulses. For example, twenty toone hundred laser pulses may be used to increase the amount of datacollected from the material and thereby obtain a more accurate analysis.

Furthermore, use of a plurality of CCD detectors enables relativelyshort CCD detector arrays to be used, which reduces the transfer time ofdata from the CCDs to the computer when compared to configurations usingvery long CCD arrays. Moreover, the apparatus provides good dynamicrange. Dynamic range is an important concept in any analyticalinstrument. Ideally, instruments are designed to detect diluteconcentrations of elements or compounds. However, they need to bedesigned so that they can determine high concentrations as well, thuswidening their potential applications. In the present apparatus, thedynamic range is determined by two factors.

Firstly, the dynamic range is determined by the sensitivity of thespectrometer system. This is a function of the sensitivity andresolution of the CCD's plus the level of light transmittance to thedetector (which may be adjustable by the use of filters, for example).

The second method of adjusting dynamic range is related to the power ofthe laser. The sensitivity of the technique (i.e. the detection limit)is critically dependent on laser power. Adjusting the laser powertherefore offers a convenient way of widening the dynamic rangeavailable to the user. Adjustment of the laser power in the presentapparatus may be conducted by varying the timing or control circuitry orby a number of other methods available to the instrument designer. Thisis a further advantage of the present invention.

It will be appreciated that the invention described herein may besusceptible to a number of variations and modifications other than thosespecifically described. In particular, although FIG. 1 shows the use ofmultiple spectrometers, a single multi-channel spectrometer may be used.However, each channel of such a multi-channel spectrometer would have adedicated CCD detector (or other suitable detection means) associatedtherewith.

The optical systems used to focus the laser light onto the sample and tofocus the emitted light onto the detection means may be of anyparticular design and still fall within the scope of the presentinvention.

The apparatus of the present invention can be used as a laboratoryinstrument or as an in-field instrument. The apparatus and method of thepresent application analyse emitted light and not reflected light andthus it is not necessary that the surface of the material being analysedbe exactly aligned with the light collection optical system. This allowsthe apparatus to be used in situations where sample preparation is notcritical. With particular regard to its use in coal analysis, thein-field instrument may be used to analyse coal travelling on a conveyorbelt. In this system, the laser may directly impinge upon coaltravelling along the conveyor belt, with the detection means arranged todetect the spectral emissions from the material on the conveyor belt.Alternatively, a sampling apparatus may remove a sample of coal from theconveyor belt for analysis by the apparatus in close proximity to theconveyor belt to thereby provide a real time analysis of the coal on theconveyor belt. It is also to be understood that the present inventioncan be used to analyse materials other than coal in the field.

The apparatus may also be used as an in-hole or in-ground instrument foranalysing coal in coal seams. In this embodiment, a sampling head may belowered down a hole bored in the coal seam. Alternatively, if the coalseam is relatively soft, the sampling head may be included as part of apenetrometer or other penetrating instrument that is pushed into thecoal seam. The Sampling head may be optically linked to the detectionmeans by an optical system that includes one or more optical fibres suchthat the detection means can be located remotely from the sampling head.This allows the size of the sampling head to be minimised Turning now toFIG. 3, an in-ground analyser includes laser analysis system 50 thatincludes a laser. Fibre optic cable 51 is linked to lens system 52 andallows laser light from laser analysis system 50 to be passed to thezone of material to be analysed. A bore hole 54 is either pre-drilled inthe ground or formed by a penetrometer.

The optical fibre cable 51 and lens system 52 are housed within a stronghousing 55 that is inserted into the bore hole 54. Housing 55 includes aclear window 53 located adjacent lens system 52. This is more clearlyshown in the inset in FIG. 3. This allows the laser light to impingeupon the coal adjacent the clear window 53 to form a plasma. Theemission spectra of the plasma is returned via fibre optic cable 51 tothe laser analysis system 50 for analysis. The laser analysis system 50is, in this regard, essentially identical to the apparatus as shown inFIG. 1.

As an alternative to the embodiment shown in FIG. 3, the laser can bedirectly mounted in housing 55 and lowered into the ground.

FIG. 4 shows an alternative apparatus for in-situ analysis. Theapparatus includes a laser analysis system 60 that is essentiallyidentical to that shown in FIG. 1. In order to analyse material from theground, a drill bit 61 and drill stringer 62 excavate a bore hole 63.Compressed air is passed downwardly through drill stringer 62 (with thedirection of air flow in drill stringer 62 being shown by arrow 64) andsubsequently moves upwardly through the annular space defined betweenthe outer wall of drill stringer 62 and bore hole 63, as shown by arrows65. The upward flow 65 of air entrains cuttings from drill bit 61 andthese cuttings are then delivered to laser analysis system 60 foranalysis. Delivery of the cuttings is shown schematically by referencenumbered 66.

Analysis of coal on a conveyor belt is shown schematically in FIG. 5. Inthis Figure, a layer of coal 70 travelling on conveyor belt 71 issubjected to a laser beam 72 emanating from laser analysis system 73.Laser analysis system 73 is essentially identical to the apparatus shownin FIG. 1. The fluorescence spectra 74 emitted from the coal is thenanalysed by laser analysis system 73.

An alternative apparatus for analysing coal on a conveyor is shown inFIG. 6. In FIG. 6, features in common with FIG. 5 are denoted by thesame reference numerals as FIG. 5. The apparatus of FIG. 6 differs fromthat of FIG. 5 in that the apparatus of FIG. 6 includes a samplingsystem 75 that extracts a sample of coal from the conveyor, which sampleis subsequently analysed by the laser analysis system 73. Afteranalysis, the sample is returned to the conveyor and a fresh sample istaken for analysis.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It will be understood that the present inventionencompasses all such variations and modifications that fall within thespirit and scope.

What is claimed is:
 1. An apparatus for analysing a material,comprising: a laser for impinging laser light onto the material tovaporise and ionise at least part of the material and to cause spectralemissions therefrom; a plurality of spectrum detection means fordetecting spectral emissions from the material, each of said pluralityof detection means detecting a part of the spectrum of the spectralemissions; a plurality of data collection means, each of the pluralityof detection means being associated with a respective one of theplurality of spectrum detection means such that each of the plurality ofdata collection means collects data from its associated spectrumdetection means; control means for controlling the firing of the laserand for controlling and synchronising the operation of the plurality ofthe spectrum detection means simultaneously to simultaneously detect thespectral emissions from the material across the spectrum of spectralemissions; and determining means connected to each of said plural datacollection means for receiving data collected thereby for determiningthe presence and amount of one or more elements or species in thematerial, said determining means simultaneously analysing the datacollected by each of the data collection means.
 2. Apparatus as claimedin claim 1, wherein each of the plurality of spectrum detection meanscomprises a spectrometer adjusted to detect a contiguous part of thespectral region.
 3. Apparatus as claimed in claim 2, wherein each of theplurality of spectrum detection means comprises a spectrometer adjustedto detect a contiguous part of the spectral region and to detect anoverlapping portion of an adjacent part of the spectral region. 4.Apparatus as claimed in claim 2, wherein the spectrometers are selectedfrom grating and prism spectrographs, interferometers including etalonand scanning interferometers, and filters including coloured glass orinterference filters which allow transmission or reflection of a portionof the spectrum.
 5. Apparatus as claimed in claim 1 wherein, each datacollection means comprises a data acquisition card; wherein saidplurality of spectrum detection means includes a plurality ofspectrometers; wherein said control means controls the simultaneousoperation of said plural spectrometers; and wherein said control meanssimultaneously turns on said plural spectrometers at a short time aftersaid laser is fired, said plural spectrometers being otherwise turnedoff.
 6. Apparatus as claimed in claim 1, wherein each of said pluralityof spectrum detection means comprises a spectrometer having a CCDdetector associated therewith, wherein each data collection meanscomprises a data acquisition card circuit, and wherein each dataacquisition card circuit receives data from the respective CCD detectorassociated therewith.
 7. Apparatus as claimed 1, wherein the controlmeans includes a timing circuit to fire the laser at specified times andto turn on the detection means at other specified times thereafter. 8.Apparatus as claimed in claim 1, wherein the control means operatesunder the direction of control software to send a control signal whichcauses the laser to emit a pulse of laser light and to send a controlsignal to each of the plurality of spectral detection means which turnson said spectral detection means.
 9. Apparatus as claimed in claim 1further comprising an optical system having a first portion for focusinglaser light on the surface of the material for creating a plasma emittedlight and having a second portion for collecting said spectral emissionsand for focusing the spectral emissions on the plurality of detectionmeans wherein the surface of the material is free of alignment with saidsecond collecting portion of said optical system.
 10. Apparatus asclaimed in claim 1, wherein the laser is selected from the groupcomprising solid state lasers including 1064 nm Nd:YAG lasers, harmonicwavelengths of the Nd:YAG laser being 532 nm, 355 nm and 266 nm, gaslasers including excimer lasers, 308 nm XeCl and 248 KrF excimer lasers,carbon dioxide lasers, liquid lasers including dye lasers, and anywavelength/frequency shifting laser with harmonic generation or mixingthereof.
 11. Apparatus as claimed in claim 1, wherein the spectrumdetection means is selected from the group comprising photodiode arrays,vidicons, photomultiplier tubes and photodiodes; and wherein saidspectrum detection means is capable of detecting emissions in theinfrared, visible light and ultraviolet ranges.
 12. Apparatus as claimedin claim 1, wherein said laser impinges upon material traveling on aconveyor belt to thereby effect analysis of the material on theconveyor.
 13. Apparatus as claimed in claim 1, wherein the apparatuscomprises an in-hole or in-ground instrument for analysing material inthe ground.
 14. Apparatus as claimed in claim 13, wherein the apparatusincludes a sampling head for being lowered down a hole.
 15. Apparatus asclaimed in claim 13, wherein the apparatus includes a sampling headcarried within a penetrometer or other ground penetrating instrument.16. Apparatus as claimed in any one of claims 14-15, wherein thesampling head is optically linked to the detection means by an opticalsystem that includes one or more optical fibres wherein the detectionmeans is located remotely from the sampling head.
 17. An apparatus toanalyze material by laser induced breakdown spectroscopy (LIBS),comprising: a laser for impinging laser light onto a material to createspectral emissions as a function of the elements present thereon; aplurality of spectrometer means operating in parallel, each of saidplural spectrometer means detecting a predetermined contiguous part ofthe spectrum of spectral emissions; a plurality of data acquisitioncircuits, connected one each to a respective one of said spectrometermeans for collecting spectral data from said connected spectrometermeans; controller circuit means connected to said laser and to each ofsaid spectrometer means for controlling the firing of a laser pulse andat a selected time thereafter for simultaneously triggering on each ofsaid plural spectrometer means for detecting said spectral emissions;and computer means connected to each of said data acquisition circuitsfor receiving said spectral data collected when each of saidspectrometer means is simultaneously triggered on, said computing meansanalyzing said spectral data.
 18. The apparatus of claim 17, whereinsaid plural spectrometer means and said plural data acquisition circuitsare adjusted for values in the visible light range.
 19. The apparatus ofclaim 17, wherein said plural spectrometer means and said plural dataacquisition circuits are adjusted for values in the infrared, visiblelight, and short wavelength ultraviolet range.
 20. The apparatus ofclaim 17, wherein said laser is triggered on by said controller circuitmeans, wherein each of the spectrometer means is simultaneouslytriggered on for a pre-selected period of time; wherein eachspectrometer means includes a spectrometer and a CCD detector connectedto said spectrometer; wherein a respective one of said data acquisitioncircuits is connected to a respective CCD detector; wherein saidcontroller circuit means is also connected to said computer means, theoperation of said controller circuit means being directed by softwareresident in said computer means; and wherein said controller circuitmeans is also connected to each of said CCD detectors to simultaneouslytrigger on each for said pre-selected period of time.